scholarly journals The Vertical Structure and Ultraviolet Spectrum of X‐Ray–irradiated Accretion Disks in Active Galactic Nuclei

1997 ◽  
Vol 476 (2) ◽  
pp. 605-619 ◽  
Author(s):  
Mark W. Sincell ◽  
Julian H. Krolik
Keyword(s):  
Active Galactic Nuclei ◽  
Accretion Disks ◽  
Vertical Structure ◽  
Galactic Nuclei ◽  
Ultraviolet Spectrum ◽  
X Ray

scholarly journals The Scaling of Solar Flare Hard X-ray Emission to Other Flaring Objects in the Universe

2000 ◽  
Vol 195 ◽  
pp. 133-134
Author(s):  
P. C. H. Martens
Keyword(s):  
Active Galactic Nuclei ◽  
Accretion Disks ◽  
Galactic Nuclei ◽  
Physical Parameters ◽  
X Ray ◽  
Transport Code ◽  
Type Particle ◽  
Fokker Planck Equations ◽  
The Universe ◽  
Fokker Planck

Fletcher & Martens have successfully modeled solar hard X-ray sources observed at the top and footpoints of flaring magnetic loops with a Fokker-Planck type particle transport code. I show here that there are invariances in the Fokker-Planck equations that make these results applicable to environments with vastly different physical parameters, such as hard X-ray flares in accretion disks in active galactic nuclei, and in RS CVn and ALGOL type binaries.

scholarly journals The role of failed accretion disk winds in active galactic nuclei

2019 ◽  
Vol 15 (S356) ◽  
pp. 82-86 ◽  
Author(s):  
Margherita Giustini ◽  
Daniel Proga
Keyword(s):  
Active Galactic Nuclei ◽  
Accretion Disks ◽  
Galactic Nuclei ◽  
Broad Line ◽  
X Ray ◽  
Broad Line Region ◽  
Line Region ◽  
Gravitational Pull ◽  
Theoretical Evidence

AbstractBoth observational and theoretical evidence point at outflows originating from accretion disks as fundamental ingredients of active galactic nuclei (AGN). These outflows can have more than one component, for example an unbound supersonic wind and a failed wind (FW). The latter is a prediction of the simulations of radiation-driven disk outflows which show that the former is accompanied by an inner failed component, where the flow struggles to escape from the strong gravitational pull of the supermassive black hole. This FW component could provide a physical framework to interpret various phenomenological components of AGN. Here we briefly discuss a few of them: the broad line region, the X-ray obscurer, and the X-ray corona.

scholarly journals Hot Accretion Disks and the High Energy Background

1983 ◽  
Vol 104 ◽  
pp. 345-346
Author(s):  
M. Kafatos ◽  
Jean A. Eilek
Keyword(s):  
Active Galactic Nuclei ◽  
Accretion Disks ◽  
Spectral Range ◽  
Gamma Rays ◽  
Gamma Ray ◽  
Galactic Nuclei ◽  
Seyfert Galaxies ◽  
High Energy ◽  
X Rays ◽  
X Ray

The origin of the high energy (X-ray and gamma-ray) background may be attributed to discrete sources, which are usually thought to be active galactic nuclei (AGN) (cf. Rothschild et al. 1982, Bignami et al. 1979). At X-rays a lot of information has been obtained with HEAO-1 in the spectral range 2–165 keV. At gamma-rays the background has been estimated from the Apollo 15 and 16 (Trombka et al. 1977) and SAS-2 (Bignami et al. 1979) observations. A summary of some of the observations (Rothschild et al. 1982) is shown in Figure 1. The contribution of AGN to the diffuse high energy background is uncertain at X-rays although it is generally estimated to be in the 20–30% range (Rothschild et al. 1982). At gamma-rays, in the range 1–150 MeV, AGN (specifically Seyfert galaxies) could account for all the emission.

scholarly journals From Thin to Thick: The Impact of X‐Ray Irradiation on Accretion Disks in Active Galactic Nuclei

2007 ◽  
Vol 662 (1) ◽  
pp. 94-101 ◽  
Author(s):  
Philip Chang ◽  
Eliot Quataert ◽  
Norman Murray
Keyword(s):  
Active Galactic Nuclei ◽  
Accretion Disks ◽  
Galactic Nuclei ◽  
X Ray ◽  
The Impact

scholarly journals Soft X-rays of AGN: Emission from Accretion Disks?

1997 ◽  
Vol 163 ◽  
pp. 805-806
Author(s):  
R. Staubert ◽  
T. Dörrer ◽  
C. Müller ◽  
P. Friedrich ◽  
H. Brunner
Keyword(s):  
Active Galactic Nuclei ◽  
Accretion Disks ◽  
Galactic Nuclei ◽  
High Energy ◽  
X Rays ◽  
X Ray ◽  
Sky Survey ◽  
High Energy Tail ◽  
Low Energies ◽  
Excess Component

Soft X-ray spectra of many Active Galactic Nuclei (AGN) show structure which suggests excess emission at low energies, mostly below 1 keV. This was confirmed by the ROSAT spectra (0.1–2.4 keV) AGN in our samples which generally have steeper power law spectra than the canonical index of 0.7. The soft excess component may be the high energy tail of the big blue bump which in turn may be due to the integrated emission from an accretion disk around the central black hole.We discuss results of our spectral analysis of two different samples of AGN: 1) QSO/Seyfert-I from the ROSAT All Sky Survey (RASS) and 2) radio-quiet QSO from ROSAT Pointed Observations. The ROSAT data are combined with UV Data from IUE and hard X-ray data from various hard X-ray missions.

scholarly journals Line Emission from Accretion Disks in Active Galactic Nuclei

1989 ◽  
Vol 134 ◽  
pp. 255-256
Author(s):  
S. Collin-Souffrin ◽  
A.M. Dumont
Keyword(s):  
Active Galactic Nuclei ◽  
Accretion Disks ◽  
Line Emission ◽  
Galactic Nuclei ◽  
Radio Sources ◽  
X Rays ◽  
X Ray ◽  
Outer Disk ◽  
Inverse Compton ◽  
Inner Region

If accretion disks are present in AGN and extend to large radii they should contribute substantially to the Broad Line emission. The outer regions of the disk are indeed illuminated by a small amount of ionizing radiation. X-rays are emitted by the central inner region near the black hole, and they are either received directly by the outer disk, owing to its “flaring” shape (Cunningham, 1976), or partly reflected towards the disk by a hot Compton thin medium (Begelmann and McKee, 1983). X-ray photons are also produced through the Inverse Compton mechanism in compact radio sources located above the disk(“jet model”).

scholarly journals Gamma-Rays from Active Galactic Nuclei

1983 ◽  
Vol 6 ◽  
pp. 505-510
Author(s):  
M. Kafatos
Keyword(s):  
Active Galactic Nuclei ◽  
Accretion Disks ◽  
Gamma Ray ◽  
Galactic Nuclei ◽  
Thermal Processes ◽  
Relativistic Electrons ◽  
Massive Black Holes ◽  
X Ray ◽  
Electrons And Positrons ◽  
Γ Rays

Gamma-ray observations from active galactic nuclei (AGN) are important in trying to understand the nature of their central sources. A handful of mechanisms can give rise to γ-rays either from nonthermal or from thermal processes. Hot accretion disks around massive black holes in the centers of AGN could provide the required thermal electrons, pions and relativistic electrons and positrons to explain both the X-ray and γ-ray emission.

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